precision mediump float;

uniform vec2 u_resolution;

void main(){
    vec2 vUv=gl_FragCoord.xy/u_resolution;
    vec3 line=vec3(1.,1.,0.);
    
    float d=abs(cross(vec3(vUv,0.),normalize(line)).z);
    
    gl_FragColor.rgb=(1.-smoothstep(0.,.01,d))*vec3(1.);
    gl_FragColor.a=1.;
}